Safety lock for crane hook



Dec. 30, 1958 CLEGG 2,866,247

SAFETY LOCK FOR CRANE HOOK Filed Oct. 11, 1955 //v VE/VTOR. HAROLD A.CLEGG,

his Attorney.

United States Patent: Ofifice 2,866,247 Patented Dec. 30, 1958 SAFETYLOCK FOR CRANE HOOK Harold A. Clegg, Homestead, Pa., assignor to UnitedStates Steel Corporation, a corporation of New Jersey ApplicationOctober 11, 1955, Serial No. 539,765

1 Claim. (Cl. 24-232) The present invention relates generally to liftcranes and more particularly to a safety lock for a lift crane hook.

'It is an object of my invention to provide a safety lock which may beeasily installed on a lift crane hook for blocking the throat thereof toprevent accidental displacement of an article carried by the hook.

It is another object of the invention to provide a safety lock asdescribed above which is adapted to move into blocking position bygravity and be automatically secured in blocking position by means of acounterweighted locking member.

It is a further objectof the invention to provide a safety lock asdescribed above wherein the locking member can be released by positivemanipulation only.

It is a further object of the invention to provide a safety lock for alift crane hook which is simple and rugged in construction and positivein operation.

These and other objects will become more apparent after referring to thefollowin specification and attached drawings in which:

Figure l is a side elevational view showing the safety lock of theinvention in closed position;

Figure 2 is a view similar to Figure 1 showing the safety lock of theinvention in open position; and

Figure 3 is an end view looking toward the left of Figure 1.

Referring more particularly to the drawings, reference numeral 2designates a crane hook having the safety lock of my invention installedthereon. The hook 2 is conventional in structure and is comprised of ashank 6, body 8, point and throat 12.

A split bracket 14 having two parallel spaced arms 16 projectingoutwardly therefrom is mounted on the shank 6 of the hook by nut andbolt means 18. The arms 16 project in a plane spaced above the throat 12of the hook. A latch bar 20 is pivotally attached at one end between thearms 16 by means of a pivot pin 22 which is attached to and extendsbetween the lower inside corners of arms 16. The latch bar 20 is of suchlength as to span the throat 12 and engage the tip portion 10 with itsfree end 24 when the bar is pivoted downwardly from the bracket, asshown in Figure 1.

A counterweighted locking member 26 is pivotally mounted between thearms 16 by means of a pivot pin 28 which is attached to and extendsbetween the upper and forward portions of the arms 16. The lockingmember 26 is provided with a straight side 30 which contacts the uppersurface 32 of the latch bar when the latter is in elevated or openposition, as shown in Figure 2. The locking member 26 is also providedwith an enlarged counterweighted portion 34 which has a cam surface 36which engages and locks the latch bar 20 against the point 10 of thehook. The latch bar 20 is normally in locking position as shown inFigure 1 since it is free to pivot by its own weight.

In operation, to elevate the latch bar 20 to open position the lockingmember 26 is rotated in the clockwise direction by applying forcemanually against the surface ance of the throat of the hook at alltimes.

38 thereof. After the locking member has been rotated to the positionshown in Figure 2 the latch member is lifted and held in elevatedposition until the crane hook is loaded or unloaded. Then the latch baris released causing it to fall against the tip portion iii of the hookand again block the throat 12. The latch bar is automatically locked inthis position by means of the locking member 26 which due to itscounterweighted shape rotates counterclockwise when the latch bar isreleased and engages the upper surface 32 of the latch bar with its camsurface 36. Thus, the latch bar is maintained in locking position by thelocking member regardless of the pressure which may be applied to itsunderside by the shifting of rings, slings or other articles beingcarried on the hook. It will be seen that the safety lock of myinvention provides a positive means for restricting the clear- Althoughit assumes locking position automatically it requires manualmanipulation of the locking member 26 to release the safety lock fromlocking position.

While one embodiment of my invention has been shown and described, itwill be apparent that other adaptations and modifications may be madewithout departing from the scope of the following claim.

1 claim:

. In a crane hook having a shank, a curved portion in the shape of a bowextending arcuately downwardly and then upwardly from the lower end ofsaid shank, a tip portion on the upper free end of said curved portion,said tip portion and said shank defining a throat therebetween, theimprovement therewith of a safety lock which comprises a bracketremovably mounted on said shank, said bracket including a split collarbody portion removably mounted around said shank, a pair of spacedparallel arms projecting from said body portion in a horizontal planeabove said throat, a pivot pin extending between the inner and lowerends of said arms, a latch bar pivotally mounted by one end on saidpivot pin between said arms, said latch bar being of such length as tospan said throat and extend to said tip portion for engagement therewithto block said throat when the latch bar is pivoted downwardly from saidbracket, said latch 'bar being freely pivotal on said pin whereby itnormally assumes throat-blocking position by gravity through its ownweight, a second pivot pin extending between the upper and outer ends"of said arms, a counterweighted locking member for said latch barpivotally mounted on said second pivot pin, said locking member having astraight side which contacts a side of said latch bar when said latchbar is in elevated position away from said point, said locking memberhaving an enlarged counterweight portion with a cam surface adjacentsaid straight side for engaging said latch bar when the latter is inengagement with said tip portion in throat-blocking position, saidenlarged counterweight portion being remote from said bracket whereby torotate said locking member by gravity to engage the cam surface of saidlocking member with said latch bar to lock the bar against said tipportion when the free end of the latch bar is pivoted toward said tipportion away from said bracket.

References Cited in-the file of this patent UNITED STATES PATENTS375,571 Sears et a1. Dec. 27, 1887 1,530,010 Neilson Mar. 17, 19251,669,805 Beer May 15, 1928 2,595,450 Coiling May 6, 1952 FOREIGNPATENTS 6,085 Great Britain 1914 87,812 Switzerland Jan. 3, 19211,100,137 France Mar. 30, 1955

